The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art.
Known vehicle powertrain system systems include one or more torque actuators coupled to transmissions that transfer torque to a driveline for tractive effort. Torque actuators include internal combustion engines and electric motor/generators. An electric motor/generator may be used in a belt-alternator-starter (BAS) system as a torque actuator in place of an alternator. BAS systems include a serpentine belt to transfer torque between the engine and the electric motor/generator. BAS systems use a high-voltage energy storage system supplying high-voltage electrical power through an inverter to an electric motor/generator.
Inverters employ power switches, e.g., integrated gate-drive transistors (IGBTs) to convert high-voltage DC electrical power to high-voltage AC power that is transferred to an electric motor/generator to generate torque for tractive effort and engine starting. Faults in such systems include line-to-line electric shorts and ground faults in any one of the inverter, the electric motor/generator, and a multi-phase power bus electrically connected between the inverter and the electric motor/generator. Faults associated with power switches and windings of the electric motor/generator may result in excess electric current flow through the various components, and an increased voltage magnitude across a collector and emitter of one or more of the power switches, referred to as desaturation. A desaturation condition is said to exist if the voltage magnitude across a collector and emitter of a power switch rises above a threshold, e.g., 5-8 volts when a gate-emitter voltage is high. Known control system responses to a desaturation fault include an immediate shutdown of the electric motor/generator. Known systems are configured to monitor power switch collector-emitter voltages to detect desaturation faults, and include control systems to effect immediate shutdown of the electric motor/generator upon detection of a fault. Powertrain systems are exposed to external disturbances including electromagnetic interference (EMI) that may trigger false detection of a fault and an associated immediate shutdown of the electric motor/generator that is unnecessary.